Safety-valve



G. H. CLARK.

SAFETY VALVE- APPLICATION FILED MAR. 30, I920.

Patented May 31, 1921.

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MASSACHUSETTS, A conronarron' or ser ers-verve.

Specification of letters Patent. *Pggtenmd M 31 192 1 Applichtion hled March 30, 1920. serial No. 869,951.

To all 'uihom'z't may concern;-

Be it know'nthat I, GEORGE HALL CLIARK,

a citizen-of the United States, and resident of Melrose in the county of Middlesex and State of Massachusetts, have invented new and useful Improvem ts in Safety-Valves, of which the following is a specification.

' My invention relates to that class of safety I valves which is characterized by a'single alve disk seating upon concentric seats, and as for its main. object the provision of effective and convenient means for ad'usting ,the controller which by progressive y con- "stricting' the efi'ective areao'f egress aper- 1-5 tures leading fromthe inner of the concen 'tric valve seats as the valve disk rises and, reversely, progressivel enlargin the said efi'ective area as the va ve disk su sides, are fords control of the lift and subsidence of the valve disk. -Oth'er structural. advantages will transpire from the description of 7 my improved valve which follows.

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single seated type of een observed-that these valves have a considerably lower sustained lift at popping pressure than the lift to In the prevailing which they rise momentarily at the pop, and that the difi'erence between these two degrees of lift is greater than the increase in sustained lift gained by the standard-permissible 3% accumulatiqnh Liftin means em ployed to assist such 'agvalve uring its accumulation period will necessarily be. active ture, and also on the rate at which this area a at "the pop, and the valve will immediately pop into its high lift, for, if the lifting means does not become active at the moment of pop, a 3% accumulation will not suffice to brin it into action. With a double seated valve, owever, the egress apertures from one of the concentric valve seats'may be employed with suitable controlling means so that the efi'ective area of such egress a cry tures shall be progressively constricted as the-valve disk rises to predetermined points of lift; thus effectiveness of-control may keep pace with changing conditions and is a powerful factor whencontrol is most needed.

The redetermination-of the behavior of a valve isk depends on'i adjustment of the initial effective cross section of control apex isdiminished as the valve disk rises, and on 'the relatioiibetween these two factors. Nice reg' ulation requires accurate and easily mawas 'iiipiilate'd adjusting devices, and these are provided by the improved valve structure herein described.

he drawing hereto annexed illustrates a safety valve, in vertical cross section, in wh ch my improvement is embodied.

he safety valve illustrated in this drawing 5: provided with the usual means for attac 'ment'to the boiler shell or the like and with other adjuncts which being well knownand is centrally lecated in the base and the,

valve disk D carries avtubular member T of which the interior space T is" open at both top and bottomcommunicatin at the top with theegress passage E whic terminates in discharge apertures E in theo'uter peripheryof the valve disk D, The tubular member T is provided with a number of apertures A all of which are adjacent to the valve seat Siwhen the valve disk is in closed position. A'sleeve R threaded into the lower end of the hood, M makes a slidin fit with the outer periphery of the disk and the lower lip of the said sleeve may be made to cover more or less of the egress apertures E according as the sleevelt is screwed down or up in relation to the seating valve disk. In order to provide easy access to the disk D for purposes of adjustment and regulation the screw ,plug P carrying the retaining pin vP is threaded into the valve casin from which it may be removed to ether with the pin P whenever it is desire to change the adjustment of the regulating sleeve R. The sleeve R is provided at intervals on its eriphery with lugs R which serve as ho ds for a suitable instrument inserted through the threaded aperture through which the plug P has been removed and which lugs also engage with the pin P to retain the said regulatin disk in any position to which it has been a justed. v

men the steam pressure resisted by the s ring G has reached a predetermined value t e valve disk D is started from its seat and when lifted a'shoirt distance the apertures A are uncovered and steam passing through roe 15 E" are circular in cross section would also as degree pf sustained lift may be obtaine them enters the tubulaiinterior T v of the member. T pro'ducin therein an auxiliary liftin ressure whi'c assists in lifting the disk The measure of this auxiliary lifting force depends on the freedom with which steam ispermitted, to cape through the egress apertures E. I make this initial lifting. pressureconsider, able so as to overcome the resistance of the spring G- and produce .an immediate in crease of lift of the disk the regulating sleeve R should be adjusted downwardly so as to produce an initial restriction er the egress apertures E. Such an ad ustment or the regulating sleeve provided the apertures.

produce a relativelyrapid rate of further constriction of the egress apertures as the valve disk rises and the disk will therefore immediately assume and maintain its 'pre- I regulation so that within the extreme limits of its susceptibility to lift-adjustment. an

as boilerpressure subsides the progressive verse :sure 0 the'valvefwith a minimum of blow it be desired to neeopea increase ofefiective area of the egress apertureslE' diminishes the total lifting pressure on the under side of the valve disk in a rerogressionand insures prompt clodown. r

I claim-i 1. In a safety we, a base providedfwith 'concentric-.seats, and-' a central well, a valve disk seating on both. inner and outer seats,

and provided with a tubular portion slidably mounted in said oentralvwell, apertures between the interior of said tubular portion charge opening from the; valve disk outside the outer valve seat, a sleeve, adjustably mounted in the-valve easing,- makin a slidfandvthe inner valve-seat, an eg ess conduit from-said tubular portion having its dis-' ing fit with the outer periphery of the disk r and coacting with said 'egressoonduit to constrictjtheefl'ectiveaperture thereofas the valve-disk rises? l 2. In a safety'valve, a' base provided with concentric valzve seats, a valve .disk seating on both inner and outer seats, and provided with a passage from its central portion within the inner, valve 'seat'to. its periphery beyond the outer valve seat, and a sleeve adjustably mounted in' the valve casing, male.

mg a sliding fit with the outer periphery of the disk, and coacting with the peripheral terminus of said passage in the valve,

1 to constrict the effective egress aperture thereof as the valve 0% sk rises. as

Signed by me atostom', Massachusetts, this 23rd day of March 1920.-

shorten CLARK. 

